1. Field of the Invention
This invention relates to latching mechanisms for stacked drawer arrangements, for example, in filing cabinet, which mechanisms act to allow withdrawal of only one drawer at a time. Such arrangements are intended to maintain the stability of the stack against tipping.
2. Background of the Invention
The provision of anti-tip latching arrangements has presented a large number of practical problems and a large amount of prior art exists. Generally, anti-tip mechanisms require great precision in installation of the anti-tip interactive components secured, for example, to a filing cabinet, and of the related actuating pins carried by the cabinet drawers.
There are at least two basic arrangements conventionally used. In the first of these arrangements, each drawer is associated with a single vertical bar of similar height to the height of the respective drawer. Each bar is itself associated with a stop to prevent withdrawal of its associated drawer. The bars and their stops are positionable such that all the stops except one are located to block withdrawal of their respective drawers.
In the second conventional arrangement, each drawer is associated with a pair of vertical bars (split bars), each pair being associated with a stop for the respective drawer. The system works in a somewhat similar manner to that described for the first system, but this second system may be more versatile in that each stop may be located at the junction between bars of each pair and the length of each bar of the pair may be selected at will.
When using the second, split bar system, it may be possible to locate stops on or about the level of the drawer track. In fact, U.S. patent application No. 384,792 to Pratzer and assigned to the same assignee as the present invention, discloses and claims a system which is mountable on a drawer track rather than on the filing cabinet wall or other wall as was previously thought necessary. This may allow for some degree of lesser accuracy in installation.
Other patents representative of the art are U.S. Pat. No. 4,768,844 issued Sept. 6th, 1988 to Ludwig and U.S. Pat. No. 4,429,930 issued February 1984 to Blouin.
While the prior art is replete with examples of anti-tipping mechanisms some general problems remain. Among these are the fact that it is necessary to provide both an upper and a lower stop for the vertical bars to limit the total spacing in which it is possible to adjust them. Moreover, in existing systems the positions of the upper and lower stops must be accurate so that the resultant spacing between them is accurate. Thus, if the total space available for adjustment is too large it may be possible to withdraw more than one drawer at a time. Sequential or concurrent withdrawal of two drawers may also be possible in some cases due to "sponginess" between adjacent bars, which are supposedly located in the non-withdrawal positions.